You'll also need some:
olive oil,
Salt & Pepper
Some herbs (I used rosemary)
4 cups of liquid. If you want this to be vegan you could use vegetable stock or even water. I used chicken broth.

Preheat the oven to 350F.
Break down the vegetables with your favorite knife. I enjoy this, it is somewhat Zen for me.

Put a little extra virgin olive oil (or whatever you have) in big pot. Add the vegetables except for the sweet potato and cauliflower (they will go in the oven) and the garlic.

Add a generous pinch of salt.

Cook stirring often until the onions are translucent and the fragrant.

Add the garlic.

I found some mushrooms so I put them in too.

Add the lentils.

Add 4 cups of liquid and tomatoes.

Bring to a boil, cover, reduce heat and simmer until lentils are tender - about 45 minutes.

Meanwhile...

Add about 1/3 cup (or less) of olive oil to a oven safe pan.
Add the cauliflower and sweet potatoes, a pinch of salt and the rosemary.

Toss to coat.

Put in the oven and roast, turn using a spatula or give them a good shake every 10 minutes or so. You're looking for a little browning on the edges and for the vegetables to be tender - about 35-40 minutes.

I was digging in the crisper and also found some spinach that needed to be used. Let's up the nutritional value!

Who needs meat when they have that?! Great use of a vegetable medley. Knowing what works is an essential skill for a good chef or domestic cook. You can't always go out and buy only what you need for the next recipe. You also have to be able to engineer meals from things that you just happen to have in the fridge, or leftovers from another meal.